Cross connection strip as used in telephone and like systems



A'. J. HUMPHRIEs 2,450,001 CROSS- CONNECTION STRIP AS USED IN TELEPHONEAND, LIKE SYSTEKS 3 Sheets-'Sheet l sept. 2s, 41941s.

Filed May 9, 1946 A. J. HUMPHRIES CROSS ONNECTION STRIP ASUSED IN Sept.28, 1948.

. TELEPHONE AND LIKE SYSTEMS Filed lay 9, 1946 3 Sheets-Sheet 2 OBOOO'O`e 8 .fr/6 6... V /8 28 42 MGI/5. 42 fs F/G. 6a.

Sept. 28, 19481. A. J. HUMPHRlEs 2,450,001

CROSS CONNECTION STRIP AS USED IN TELEPHONE AND LIKE SYSTEMS Filed May9, 1946 3 Sheets-Sheet 3 lll VMM/

tta/wea Patented Sept. 28, 1948 UNITED STATES CROSS CONNECTION STRIP ASUSED IN TELEPHONE AND LIKE SYSTEMS Arthur James Humphries, Harrogate,England, assigner to International Standard Electric Corporation, NewYork, N. Y., a corporation of Delaware Application May 9, 1946, SerialNo. 668,354 In Great Britain October 18, 1944 Section l, Public Law 690,August 8, 194.6 Patent expires October 18, 1964 3 Claims. (Cl. 173-324)The present invention concerns improvements in or relating to connectionstrips as used in telephone and like systems and more particularlyalthough not exclusively concerns the construction of a cross connectionstrip which is used in a distribution cabinet or street pillar forconnecting conductors in a cable extending from an exchange to otherconductors in a cable extending eventually to subscribers premises. Itwill be understood that connection strips can be used at two or morepoints between the exchange and the subscribers cable and in othersituations if required or desired.

Distribution cabinets have to be located in convenient positions withregard to the locality they serve and must be readily accessible for theconnection of new subscribers and the disconnection of subscribers whoseservice is terminated. Consequently consideration has to be given to thefollowing features. Firstly the contact members must be satisfactorilyinsulated even under adverse conditions as regards ingress of moistureand dust and at the same time the contacts must be reliable in serviceand free from any tendency to disconnection due to vibration or otherexternal disturbances. Secondly the jumper field should be neat andorderly and maintained in this manner throughout the full period duringwhich the installation is in use. Thirdly the cabinet in which the crossconnected strips are mounted must be of such appearance and dimensionsas to be suitable for the position in which they require to be locatedso as tofacilitate the granting of the necessary way leaves and it is anobject of the present invention to provide a cross connecting stripcapable of meeting the above conditions in a most satisfactory way.

According to 'one feature of the invention the contacting surfaces areso locatedwithin the insulation of the connecting strip that ingress ofdust or moisture therein is substantially eliminated or at least reducedto a minimum in the most adverse conditions.

According to another feature of the invention use is made of straightbare bridging wires, the connection strip being arranged to permit easyand positive insertion of bridging wires as far as possible. The crossconnecting strip consists of .t two rows of terminals to one ofwhichrows the across as between corresponding terminals in the two rows andthat only a comparatively small number of the connections need to bemade by means of jumper wires, that is to say by connections betweenterminal/which are not immediately opposite to each other.

Accordingto a third feature o! the invention the connection` to two ormore wires is eitected through the medium of a single screw, termed thecontact screw, the necessary pressure being transmitted to the contactsurfaces through a pressure block which consists of a shaped insulatedand guided block designed to press the individual wires against theirrespective contact members.

The invention will be better understood by reference to the accompanyingdrawings which illustrate by way of example a cross connection strip forpairs of wires in accordance'with the 2o invention.

In the drawings:

Fig. 1 is a plan view of a cross connection strip.

Fig. 2 is a part elevation and part sectional elevation of the strip online 2m of Fig. 1.

Fig. 3 is a sectional elevation on the staggered line YY of Fig. 1.

Fig. 4 is a sectional side view on the staggered line ZZ of Fig. 1.

Fig. 5 is a. plan view oi' a terminal block.

Figs. 6 and 6a are front and rear views respectively of a terminalblock.

- Fig. 7 is a section on the line VV of Fig. 6.

Fig. 8 is a section on the staggered line WW of Fig. 6.

Fig. 9 is a side view, Fig. 10 a plan from below and Fig. 11 a frontview of the pressure block.

Fig. 12 is a perspective view of the components of a contact-makingelement for a single pair of wires.

Figs. 13 and 14 show respectively front view and cross section on lineUU (Fig. 13) oi' guide block.

Figs. 15 and 16 show respectively section on line TT (Fig. 16) and endview of label block.

The connection strip conveniently consists of -two similar rectangularblocks li (left-hand) and i2 (right-hand) of insulating material. Therectangular blocks, which will be termed terminal blocks, are similar inconstruction and it will be suicient -to describe the construction ofone only. These terminal blocks are mounted opposite each other and aresuitably spaced apart by insulating blocks I3 and Il so thatcorresponding terminals in each strip lieimmediateiy opposite eachother. 55 It will be appreciated that one of the dimensions of theterminal block, which will be termed the length, will depend upon thenumber of terminals to be accommodated. This number is governed bymanufacturing considerations and may be varied as convenient. In thedrawings 22 pairs are provided for. The individual terminals of a pairare conveniently spaced about one-eighth of an inch apart, while theindividual lpairs have their centres about a quarter of an inch apart.

The other two dimensions will be referred to as the breadth, which isthe dimension transverse to the length of the terminal block, and isconveniently about 1/2" to 3/4" while the third dimension extending fromthe contact screws I5 to where the contact tags IB emerge will bereferred to as the depth and is approximately 11/2". It will beunderstood that these dimensions can be readily varied without departingfrom the spirit of the invention and that their choice is dependent upona number of considerations, particularly the desirability of having thecontaining distributing box as small as possible consistent withadequate spacing of the terminals for handling insulation andA likeconsiderations.

Each terminal block as will be best seen from Figs. 5 to, has internalportions cut away which are similar for each pair of. terminals, that isto say vertical sections transverse to the length could be cut awaywhich are the same for each pair of terminals. These cutaway portionsconsist ci a hole I8 shaped so as to have a part circular section -totake a brass insert I8 of' similar cross section, and having a threadedhole crossing the axis with which hole a contact screw I5 engages. Thehole and the brass insert have a length of about three-quarters of theterminal block. A circular hole I9 is provided for the contact screwitself and -a recess 20 is provided for the pressure block 2i andcontact plates 22 and 23. The recess does not extend right through theblock. The pressure block 2| is conveniently formed of insulatingmaterial, either by moulding or otherwise and is illustrated in Figs. 9,l0 and 1l. It will be noted that it consists of a block cut away todifferent heights on opposite sides, the under sides of the cuts beingchamfered at their ends as art 24 and 25. The width of .the pressureblock 2| is such as to flt neatly with little play .in `the recess 20while the breadth of the pressure block is about equal to the breadth ofthe recess 2l. The contact plates 22 and 22 'are complementary and|their shape will be best seen in Fig. 4. They each have a tag portionto `which connecting wires may be soldered, a vertical shank To allowfor manufacturing tolerances in the wires and in the components of thestrip, the contact plates 22 and 23 are serrated on their upper faces.The serrations which Iby penetra-tion of Pthe wire or by themselvesbecoming deformed uneasily followed.

In the complete cross-connecting strip as illustrated in Figs. l, 2, 3and 4, there are two identical terminal blocks II and I2 convenientlyformed by moulding a phenol condensation product. the construction ofthese blocks being fully disclosed in Figs. 5, 6, 6a, 7 and 8, aguideblock Il similarly formed, the construction of which is illustrated inFigs. 13 and 14, and a label block I3 which is also similarly formedland the construction of which is illustrated in Figs. 15 and 16. Thegeneral ar-`-. rangement of these blocks is best illustrated in' Fig. 4which also shows long contact plates 23* and short contact plates 22 inposition.

The blocks are secured together by clampingrods 33a which are shorterlat the top than at the bottom. The clamping rods are threaded at their'and a horizontal extending contact-making element, and are convenientlyformed by a simple blanking tool. The contact-making element ischamiered to facilitate inserton of a conductor.

The recess 20 is provided with a shelf at one side on which thecontact-making element of plate 23 may rest while the contact-makingelement of plate 22 rests on the base of recess 20 as clearly shown latlthe left-hand side of Fig. 2.

In operation wires inserted between .the vserrated surfaces of thecontact members 22 and 23 and the underside of the cut-away portions oneach side of the pressure block 2i are secured in position by a singlescrew I5 which on being turned presses at its end on the pressure yblock2i due to its engagement with the threaded hole of insert Ita causingthe wires to be gripped tightly between the serrated surfaces of thecontact plates 22 and 23 and the upper parts of the cut`4 away portionson each side of pressure block 2l..

ends and pass through holes in the terminal:

blocks and an intermediate block which may be either the label block orthe guide block according' as to whether the upper or lower clampingrods are referred to.

Nuts engaging with the threaded ends secure sets of ten holes I9 for thecontact screws I5,r

along the base but visible in the plan are two sets of ten grooves 21which serve as guides for the in- E terconnecting pairs of wires.

Embossments 28 which extend round the outercorners of the top of theterminal 'block land down one side serve as'guides to denne the positionof a cable pair and are alternatively long and short as will be bestseen when viewed in Fig. 6.

Looking at Fig. 6 -it will be noted that there are Itwo sets of tenpairs of holes 29, 30 for the admission of the ends of the wires to beconnected. the holes are oval in shape to permit, when necessary. fortwo wires to be inserted together. The holes 29 and 3II are displaceddiagonally -to increase the clearance between wires when inserted.

Dividing the holes are embossed ridges 3| and 32.l Embossed ridges 3iwhich are substantially rectangular with a curved corner serve to dividethe various pairs of connecting wires or terminals while embossed ridges32 which are actually a continuation of 2l divide the individual pairsof connecting wires orterminals. 'I'hese embossed ridges extend from aprotruding 'part of the lterminal block and where lthey loin such partthey provide semi-circular bases round the holes 28 and 30 wherebyv theconnecting wires may be Six holes 33 with hexagonal recesses in theleftithey hand lterminal block il and circular recesses in their outeredge lies flush with the inner side of the block. It will be noted thatthe successive pairs of contact plates are effectively insulated fromeach other by the side' walls of the recesses while the contact platesof a pair are insulated within the recesses by the central portion ofthe\ pressure block.

The guide block I4 which is illustrated in Figs. 13 and 14 is providedwith two pairs of ten grooves extending across the block, each groovehaving three different depths the lowest depth being in the middle whilethe side depths corresponding approximately to the heights oi' the holes28 and 30 respectively serve as guides for straight bridging wirespassing through said holes. Three holes 31 corresponding with the lowerholes 33 are provided each having a boss ll at each end having adiameter such as to be a neat t in the circular recesses 34.

On the lower part of the guide block i4 are two projecting ridges 39 and40 forming between them a longitudinal groove 4I extending the fulllength of the block and serving as a channel for a mounting bar to whichseveral strips may be xed preparatory to soldering wires of the cable tothe tags of contact members.

The label block i3 illustrated in Figs. 15 and 16 is a substantiallyhollow rectangular block having moulded in its upper part three metalinserts 42, having threaded holes to enable a label plate 43 (seeFig. 1) of celastoid or like material to be secured in position byscrews 44. It will be noted that the hollow in the block is open on theunderside and has ribs 4l to strengthen the somewhat thin side walls ofthe block.

Holes 46 are provided for aligning with the upper holes 23 in theterminal blocks. It will also be noted that the end pieces ot the labelblock extend beyond the plane of the base. This enables the label blockto seat in the cut-away portions at the upper' corners of the guideblock.

The manner of assembly of the cross connecting strip in the formillustrated in Figs. 1 to 4 will be readily appreciated from theforegoing description.

The method of use will now be described.

From a cable for instance extending from an exchange and a cable forinstance lextending eventually to subscribers premises and each having20 pairs of conductors, the pairs of conductors of one cable areconnected to correspon-ding tags of pairs of contact plates on one sideof the cross connecting strip and the pair of conductors of the othercable are connected to corresponding tags of pairs of contact plates onthc other side of the cross connecting strip.

To connect one pairof conductors of one cable to a pair of conductors ofthe other cable, two different methods of connection are possible withthe cross connecting strip according to the invention.

One method of connection concerns pairs of contact plates directlyopposite each other in the cross connecting strip. For this kind ofconnection all that is necessary are bare wires preferably withinsulating heads of a suitable piastic or other material. bare wires maybe Joined by a common insulating head to form a pair. I'he wires areinserted through the-holes 2| and 20 of one of the pairs of contactplates to be connected up after the contact screws il of the two pairsof contact plates to be connected together have been unscrewed. As thewires are pushed home due to the chamfered surfaces on the contactplates and the pressure block the pressure block rises permitting thewires to pass through. The ledges oril the guide block ensure the wirespassing straight towards the chamfered surfaces on the second pair ofcontact plates and the pressure block where the pressure block is raisedto permit the ends of the wires entering between the serrated surfacesof the contact plates. and the horizontal surfaces between the chamferedsurfaces of the pressure block. All that remains is to screw the contactscrews home when good electrical connection is made between the wiresand the contact plates and in consequence between the two pairs of wiresit is desired to connect together.

The other method of connection concerns pairs of contact plates whichare not directly opposite to each other in the cross connecting strip.

It is estimated in practice that the majority of connections may be madebetween contact plates directly opposite each other and that thereforeonly a limited number of connections will require to be made in themanner to be described.

Instead of bare wires it will be desirable if not essential to employinsulated-covered wires conveniently in twisted pairs with wiressuillciently stiff to pass readily through the holes 29] and I0 and toraise the pressure block substantially as previously described.

To connect two pairs of contact plates not directly opposite the baredends of a pair of insulated wires as described above are insertedthrough the holes 29 and 20 suilciently to raise the pressure block andpass on to the serrated surfaces of the contact plates, the contactscrew i5 associated therewith is then screwed home to secure the endsand establish a good electrical connection with the contact plates.J'The pair of wires are then bent over and passed through the groove 21immediately below the pair of contact plates. 'I'hey are then crossedover to pass through the groove 21 immediately below the pair of contactplates with which contact is to be established and the wires cut andends cleared of insulation suillciently to permit the cleared endspassing through the holes 29 and 30 of the latter pair of contact platesand on to the knurled surfaces thereof. The contact screw I5 associatedwith this pair of contact' plates is then screwed home and a secureelectrical connection between the two pairs of conductors made.

It will be appreciated that by this construction all parts where contactis made are enclosed in insulating materials so that deleterious effectsof the ingress of moisture and dust are minimised. If a jumperconnection is to be made the jumpers may conveniently be insulated witha polyvinylchloride covering. This provides a very neat construction andfurthermore the entrances to the connecting contacts being only justsuillcient for the wires to pass through protects the contact surfacesfrom the ingress of moisture and dust.

It will be appreciated that the invention is not strictly limited to theconstruction described.

For instance, the mechanical arrangement of op- Alternatively two suchv7 erating the pressure block and its shape may be variedl i. e. .amilled headed securing screw may be employed or instead of the metalpiece being above the pressure block it may be arranged below it, thescrew then passing through the pressure block may be arranged to lift itso that the contacts are accessible from the top. 'I'he shape of thecontact plates may also be varied. The object'of providing differentsizes of contact plates for each pair of conductors enables the contactsto be located nearer together while permitting of easy manualoperations.

I claim:

1. In a strip for cross connecting the wires of two cables, two parallelterminal blocks of insulating material each having a front, a back, atop and a bottom, a plurality of groups of tags projecting through thebottoms of the two terminal blocks and to which groups of wires of thetwo cables may be attached, each tag havinga contact surface within arecess in the corresponding terminal block, each recess being open tothe back of its block and having a shelf for each contact surface, apressure block of insulating material within each recess, movablypositioned between and separating the shelves and the contact surfaceslying thereon, each pressure block having a ledge for engaging eachcontact surface, each cooperating ledge and contact surface beingaligned with a perforation in the front of the terminal block throughwhich wires may be pushed from the front of one terminal block to thealigned perforation in the front of the other block, each wire passingbetween contact surfaces and the cooperating ledges. and meansprojecting through the tops of the terminal blocks,

A one for each pressure block to force it towards the cooperatingcontact surfaces.

2. In a trip for crossconnecting the wires of two cables, two terminalblocks of insulating material each having a front, a back, a top and abottom. a plurality of pairs of tags projecting through the bottoms ofthe two terminal blocks and to which pairs of wires of the two cablesmay be fastened, the tags of each pair being staggered, each tag havinga contact surface formed at right `angles to the shank of the tag andpositioned within a recess in the corresponding terminal block, eachrecess being open to the back of its block and having two staggeredshelves, one for the contact surface of one and the other for thecontact surface of the other tag of a pair, a pressure block ofinsulating material within each recess, movably positioned between andseparating the two shelves and the contact surfaces lying thereon, eachpressure block having on one side a ledge parallel with and engaging onecontact surface and on the opposite side a ledge parallel with andengaging the second contact surface positioned within the same recess,staggered perforations in the front of each terminal block aligned withthe contact surfaces and cooperating ledges on the pressure blocksaording open channels through which wires may be pushed from theperforations in the front on one terminal block to the alignedperforation in the front of the other block, each wire passing betweencooperating contact surfaces and ledges, and a plurality of screwsprojecting through the tops of the terminal blocks. one for eachpressure block and arranged to force it towards the cooperating contactsurfaces.

3. In a strip for cross connecting the wires of two cables, two parallelterminal blocks of insulating material each having a front, a back. atop and a bottom, an upper and a lower strip of insulating materialclamped between the blocks of the two terminal blocks, identificationcards on the upper strip, a plurality of pairs of tags projectingthrough the bottoms of the two terminal blocks and to which pairs ofwires of the two cables may be soldered, the tags of each pair beingstaggered, each tag having a serrated contact surface chamfered at twoends and formed at right angles to the shank of the tag within a recessin the corresponding terminal block, each recess being open to the backof its block and having two staggered shelves, one for supporting thecontact surface of one and the other for supporting the contact surfaceof the other tag of a pair, a pressure block of insulating materialwithin each recess, movably positioned between and separating the twoshelves and the contact surfaces lying thereon, each pressure blockhaving on one side a ledge parallel with and engaging one serratedcontact surface and on'the opg posite side a ledge parallel with andengaging the second serrated contact surface within the same recess,said ledges being chamfered at two ends to form with the chamfered endsof the contact surfaces guide holes opening towards the back and front,respectively, of the terminal block. the front guide holes being alignedwith staggered perforations in the front of each terminal block, and therear holes being aligned with staggered grooves formed in the lowerinsulating strip affording channels between aligned recesses of the twoterminal blocks through which wires may be pushed from the perforationsin the front of one terminal block to the aligned perforations in thefront of the other block, each wire passing between and being engaged bytwo serrated contact surfaces and the cooperating ledges, projections ofinsulating material on the front of each terminal block aligned with theperforations therein, a plurality of screws projecting through the topsof the terminal blocks. one for each pressure block and arranged toforce it towards the cooperating contact surfaces, and metal inserts inthe terminal blocks, one for each screw and in threaded ,engagementtherewith.

ARTHUR JAMES HUMPHRIES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,224,971 Skinner May 8, 19171,559,668 Brown Nov. 3, 1925 1,915,199 Park June 20, 1933 FOREIGNPATENTS Number Country Date 635,249 Germany Sept. 13, 1933 711,049France Feb. 12, 1931 778,958 France Sept. 27, 1934

